Means for cooling a cable passing through a cable-sheathing press



MarCh 1966 K. SEIDEL ETAL MEANS FOR COOLING A CABLE PASSING THROUGH A CABLE-SHEATHING PRESS Filed July 5, 1963 How 5 a A.

Illll lllllllllIIIII-IlllillllIW United States Patent 3,239,884 MEANS FOR COOLING A CABLE PASSING THROUGH A CABLE-SHEATHIN G PRESS Karl Seidel, Moers, and Alfred Steinmetz, Dusseldorf, Germany, assignors to Schloemann Aktieugesellschaft, Dusseldorf, Germany Filed July 5, 1963, Ser. No. 292,971 Claims priority, application Germany, July 19, 1962, Sch 31,768 2 Claims. (Cl. 18-13) This invention relates to an arrangement for cooling and protecting from radiation a cable entering a cable sheathing press through a hollow mandrel and comprising a protective tube inserted in the hollow mandrel, which forms an annular gap with the inner wall of the mandrel and also with the entering cable.

Such arrangements are known, for example, from German patent specifications Nos. 951,262 and 960,533.

When using very sensitive cable insulations, of polyethylene, for example, heat damage to the insulations occasionally occurs in spite of the protective action of the known arrangement. The object of the invention is to prevent this occasional damage through heat also and to make the arrangement suitable even for sheathing cables having an insulation which is extraordinarily sensitive to heat.

The invention is characterized by a compressed air or vacuum connection to one of the annular gaps for the purpose of creating a stream of air in the inner annular gap. Such a stream of air keeps the cable insulation at a permissible relatively low temperature, particularly if the cool air flows into the inner annular gap and flows out of the outer annular gap after being heated.

It is particularly advantageous if the protective tube extends at least as far as the tip of the mandrel. By this means air cooling is achieved in the region in which the radiation from the pressed out, still warm cable sheath acts directly on the insulation. As the space within the mandrel bore is very restricted, it will generally be only possible to design the front tube end extending as far as the mandrel tip as a single-walled tube. Cooling thereof can be achieved, however, by connecting it in a heat conductive manner to a water-cooled double pipe.

The drawing illustrates the invention with a cross-section through the arrangement according to the invention.

A press block 1 has two entry channels 2 for the material to be pressed, which channels open into the pressing chamber 3. The latter is towards the left substantially closed by the die 4 which bears against a screwed-in pressure piece 5. In the matrix 4 and the pressure piece 5 is provided a known device 6 for cooling the finished pressed cable sheath 7. This cable sheath is pressed out of the pressing chamber 3, cf. the sheath formation at 7a. The die 4 is located opposite a mandrel 8, which is retained by a screwed-in pressure piece 9. The mandrel 8 has a hollow bore 10, in which the arrangement according to the invention is located. It has in a manner known per se a double tube 11, in which are formed two cylindrical cavities 13 and 14. Into annular cavity 13 cooling water flows in the direction of the arrow 15 and it flows out of the annular cavity 14 in the direction of arrow 17 after heating.

As the mandrel is most greatly stressed in the region of its tip, it is not possible to take the bore much further forward than illustrated. The double-walled cooling device thus does not reach right to the tip of the mandrel. Instead a simple cooling and air-conducting plate 18 connected in a heat-conductive manner to the double cooling tube 11 projects into the mandrel tip. The deflecting plate 18 is continued in the deflecting plate 19, which is 3,239,884 Patented Mar. 15, 1966 likewise connected in a heat-conductive manner to the deflecting plate 18 and at its front end projects somewhat beyond the tip of the mandrel.

According to the invention compressed. air is introduced through a feed pipe 20 into the annular chamber 21 existing between the cooling pipes 11, 18, 19 and the cable 22. This air flows forwards until further flow is rendered impossible through the cable sheath 7a being formed. It therefore turns at the tip of the air deflecting plate 19 and flows back through the annular gap 23 existing between the cooling tube 11 and the mandrel inner wall 8 or the inner wall of the pressure piece 9.

The discharge of the heated air into the atmosphere is indicated by the arrow 24. In order that the blowing of air into the chamber 21 at excess pressure is possible, the annular chamber 23 is closed towards the rear by a seal 25, the sealing flap 26 of which, consisting of plastic or rubber, bears in a tight manner against the cable 22 running in to the press.

The invention is also partly carried into effect if the air conducting tubes 18, 19 are not taken quite so far to the left as shown. The invention might also be carried into effect by allowing the air to enter the outer gap 23 and be guided back through the inner gap 21. Such an arrangement, however, is less favourable from the point of View that the cable 22 is then pre-heated by the heated air before it reaches the sheathing point.

The action according to the invention can of course also be obtained by suction. The only essential feature is to create a stream of air in the gap 21.

We claim:

1. A cable sheathing press including a matrix having an opening extending therethrough, a hollow mandrel disposed in axial alignment with said opening, the forward end of said mandrel terminating in spaced relation to the rear edge of the opening in said matrix to provide an annular gap for the flow of extrusion material to form a sheath on a cable passing through said mandrel and matrix, and cooling means for the cable, said cooling means comprising inner, intermediate and outer radially spaced concentric tubular members disposed within said mandrel, said outer tubular member being spaced from the inner wall of said mandrel to provide a cooling air passage therebetween, the spaces between said inner, intermediate and outer tubular members being closed at the forward and rear ends with the space between said inner and intermediate tubular members communicating with the space between said intermediate and outer tubular members adjacent the forward ends to provide cooling water passages, a water inlet fitting for one water passage and a water outlet fitting for the other water passage, circular sealing means adjacent the rear end of said inner tubular member for engaging the outer surface of a cable passing therethrough to provide an airtight seal, the inner diameter of said sealing means being less than the inner diameter of said inner tubular member, whereby an air passage is provided between said inner tubular member and a cable passing therethrough, said inner tubular member terminating at the fOl'WflId end within said mandrel in closely spaced relationship to the forward end of said mandrel, and an air connection fitting on said inner tubular member, whereby air may flow through the air passage between said inner tubular member and said cable in either direction to cool said cable and around the forward end of said inner tubular member and through the air passage between said outer tubular member and said mandrel in either direction, said air being cooled by water flowing through said cooling water passages.

2. A cable sheathing press as defined in claim 1, in which a tubular extension is provided on the forward end of said inner tubular member, said extension projecting forwardly from said inner tubular member at least to the forward end of said mandrel.

References Cited by the Examiner UNITED STATES PATENTS 5 4 FOREIGN PATENTS 218,292 8/1958 Australia. 811,703 4/1959 Great Britain. 825,860 12/1951 Germany.

' WILLIAM J. STEPHENSON, Primary Examiner.

M. V. BRINDISI, J. SPENCER OVERHOLSER, L. S.

SQUIRES, Examiners. 

1. A CABLE SHEATHING PRESS INCLUDING A MATRIX HAVING AN OPENING EXTENDING THERETHROUGH, A HOLLOW MANDREL DISPOSED IN AXIAL ALIGNMENT WITH SAID OPENING, THE FORWARD END OF SAID MANDREL TERMINATING IN SPACED RELATION TO THE REAR EDGE OF THE OPENING IN SAID MATRIX TO PROVIDE AN ANNULAR GAP FOR THE FLOW OF EXTRUSION MATERIAL TO FORM A SHEATH ON A CABLE PASSING THROUGH SAID MANDREL AND MATRIX AND COOLING MEANS FOR THE CABLE, SAID COOLING MEANS COMPRISING INNER, INTERMEDIATE AND OUTER RADIALLY SPACED CONCENTRIC TUBULAR MEMBERS DISPOSED WITHIN SAID MANDREL, SAID OUTER TUBULAR MEMBER BEING SPACED FROM THE INNER WALLS OF SAID MANDREL TO PROVIDE A COOLING AIR PASSAGE THEREBETWEEN THE SPACES BETWEEN SAID INNER, IN TERMEDIATE AND OUTER TUBULAR MEMBERS BEING CLOSED AT THE FORWARD AND REAR ENDS WITH THE SPACE B ETWEEN SAID INNER AND INTERMEDIATE TUBULAR MEMBERS COMMUNICATING WITH THE SPACE BETWEEN SAID INTERMEDIATE AND OUTER TUBULAR MEMBERS ADJACENT THE FORWARD ENDS TO PROVIDE COOLING WATER PASSAGES, A WATER INLET FITTING FOR ONE WATER PASSAGE AND A WATER OUTLET FITTING FOR THE OTHER WATER PASSAGE, CIRCULAR SEALING MEANS ADJACENT THE REAR END OF SAID INNER TUBULAR MEMBER FOR ENGAGING THE OUTER SURFACE OF A CABLE PASSING THERETHROUGH TO PROVIDE AN AIRTIGHT SEAL, THE INNER DIAMETER OF SAID SEALING MEANS BEING LESS THAN THE INNER DIAMETER OF SAID INNER TUBULAR MEMBER, WHEREBY AN AIR PASSAGE IS PROVIDED BETWEEN SAID INNER TUBULAR MEMBER AND A CABLE PASSING THERETHROUGH, SAID INNER TUBULAR MEMBER TERMINATING AT THE FORWARD END WITHIN SAID MANDREL IN CLOSELY SPACED RELATIONSHIP TO THE FORWARD END OF SAID MANDREL, AND AN AIR CONNECTION FITTING ON SAID INNER TUBULAR MEMBER, WHEREBY AIR MAY FLOW THROUGH THE AIR PASSAGE BETWEEN SAID INNER TUBULAR MEMBER AND SAID CABLE IN EITHER DIRECTION TO COOL SAID CABLE AND AROUND THE FORWARD END OF SAID INNER TUBULAR MEMBER AND THROUGH THE AIR PASSAGE BETWEEN SAID OUTER TUBULAR MEMBER AND SAID MANDREL IN EITHER DIRECTION, SAID AIR BEING COOLED BY WATER FLOWING THROUGH SAID COOLING WATER PASSAGES. 